1. Field of the Invention
The present invention relates to gutta-percha cones for obturation of root canals and, more particularly, to an improved gutta-percha cone comprising utility length control markings on the shaft of the obturating cone to facilitate the visual ease of point of reference plane insertion into a prepared root canal. The invention also comprises a method of trial cone insertion of the above-described gutta-percha cone that allows a more efficient, precise and accurate fit.
2. Description of the Background
Typical root canal procedures include accessing the root canal, preparation of the root canal and filling or obturation of the canal with a gutta-percha cone. One key step of the root canal procedure is determining the working length of the canal so that irritating chemicals and materials are kept away from the surrounding periradicular tissues. The correct working length of the root canal is important in determining success or failure because a short or a long obturation may deter healing by causing an inflammatory foreign body response or allowing an open area for fluids and bacteria to accumulate leading to future breakdown. The length of canal procedure establishes the apical extent of instrumentation as well as the ultimate apical level of the root canal filling, the gutta-percha obturator.
The requirements for a method for determining length of the canal are that it should be accurate, it should be easily and readily performed and easy to confirm. During canal preparation, the working length of the canal is determined by a combination of radiographs and electronic canal measurements. A reference point is determined for these procedures on the coronal surface of the tooth. Once this defined point is determined to be reliable and repeatable, this becomes the all important anatomic landmark that is consistently referred back to as the reference point for obturation. A gutta-percha trial cone is then inserted into the prepared root canal. Previously the gutta-percha cone is grasped between cotton pliers and is measured by a ruler to the correct length that has been predetermined. The cone is then carried into the prepared root canal until the cotton pliers touch or match up visually to the predetermined reference point or plane. If the cone lines up correctly the visual test has been passed (unless the cone is not correctly sized or the prepared canal is larger than the cone). If the cone can be pushed deeper into the canal than the length is off and the gutta-percha cone must be trimmed back so that it fits correctly. It must then be re-measured against a millimeter ruler or gauge, and replaced visually against the reference point so that it is correct. This trial and error procedure can go on and on, ultimately changing the length by several millimeters. It is very cumbersome and time consuming, and the gutta-percha cone can become contaminated during this re-calibration. Nevertheless, it is a significant and important procedure to prevent overfilling and biologic irritation to the surrounding tissue.
It would be greatly advantageous to provide a gutta-percha cone and method of use that facilitates visual point of reference plane insertion into a prepared root canal in order to accurately, easily and reliably determine the length of the canal.